Several definitions of somatization exist and try to deal with the fundamental problem that a large group of patients present with physical symptoms for which a conventional pathology cannot be identified. However, the concept remains somewhat confusing. The prevalence of somatization is high in general practice. Nevertheless, patients do not receive proper treatment and risk iatrogenic somatic fixation and harm, the doctor-patient relationship is often negatively affected and the overall healthcare system suffers from high expenditure on unnecessary physical investigations and treatments. During the last decade research has shown that somatization may be treated effectively in specialist care. Little is known about effective treatment in primary care but the Reattribution Model and the Extended Reattribution and Management Model have shown promising results. The development and evaluation of new treatment strategies is, however, hampered by the confusion of definitions and concepts. In this article an overview is presented of the various concepts relevant to the clinical work and research in primary health care. It is important to realize that somatizing patients in primary health care present a broader spectrum of severity than patients seen in a specialist setting. Hence, primary care cannot apply definitions from specialist care directly but needs a definition that also includes the mild cases. We need classifications and agreed definitions applicable in primary health care in order to develop appropriate management strategies, to predict prognosis, and to enable rigorous research concerning the large group of somatizing patients in primary health care.